Method of drying finishes



March 25, 1941. F. E. DRuMMoND METHOD 0F DRYING FINISHES rled'Aprn 17.1959 1NvENToR.

Faso/w t pa'MMo/VD ATTORNEYS wu,... A .f

March 25, 1941. F. EDRUMMOND 2,236,397

METHOD 0F DRYING FINISHES Filed April 17, 1939 2 Sheets-Sheet 2 f Ziz-Lf f ,l l, 27 n zy/ n /q l if,

OXYGEN` OR ENRICHED RIR OXYGEN OR ENRICHED FUR W|TH OXIDATION CATALYST lFAN [IUUU [IU'UU uuuuuu HEATING ELEMENT INVENTOR.

Bywwm/ ATTORNEYS Prasad Mu. 2s, 194i UNITED STATES PATENT OFFICE l2,236,391 'e Y Marnon or prima Fmsnas renom a; Drummond, Damn, ohio,miglior, by mesnc'asaignmentl, to New Wrinkle, Inc.,- Wilmington, Del.,a corporation of Delaware Application Api-ii 17, 1939, serial No. assens claim. (or 34-24) e My invention relates to a method for drying"coating compositions, and more particularly to the method of Iproducingwrinkle finishes.. The invention, however, is adapted for acceleratingthe drying of various types of coating compositions whi'ch dry to a hardflexible lm by oxidation, polymerization, evaporation of solvents or acombination of these actions.

It `is one object of this invention to produce wrinkle finishescomprising conventional nonwrinkling oil vehicles such asv linseed,perilla, soya bean oil, poppy seed, ish oils andthe like, which oilsordinarily dry to a smooth, glossy, non-wrinkling film.

Another object is to provide a method for producing articles havingwrinkle iinishes from compositions comprising blends of non-wrinklingand wrinkling oils, which wrinkling oils include Chinawood, oiticica,and poyok in blown, .unblown` or 0 raw state.

Another object is to provide an Vimproved method of dryingcoated'compositions of the drying oil or oleoresinous type whichordinarily dry toa smooth surface so that they will dry to a wrinkleinish.

Another object is to provide an improved method of accelerating thesurface drying of coating compositions in order to produce a wrinkle orirregular surface film.

Another: object oi' this invention is to provide a controllableatmosphere for baking coated articles to cause the coating-to'dry to ahard, smooth finish or irregular wrinkle surface as desired.

Another object is to provide an enclosure for force air drying coatedarticles by means of oxygenr orA ozone enriched heated air which alsocarries small amounts of an oxidation promoting catalyst for 'increasingthe oxidation activity on the lm surface so as to produce a wrinklefinish.

Another object is to provide an improved method of accelerating theoxidation and polymerization of coating compositions applied toarticlesin' a thin iilm soV as to lessen the time for dry' ing coating illms toa dust-fre'e-nish.

In general the wrinkling of coated lms is brought 'about by unequal"drying of the film producing surface volume changes which develop'-introvertedfolds in the surface skin ofthe filmi producingi' a' wrinklefinish. In the case-of dry- I ing oil coating 'films comprisingwrinkling oils; for 'example'ichina-wood or oiticica, it has beenfound-that v4'folds or wrinkling of the illm surface may be broughtabout by excess oxidation and polymerization `at the surface of the lm.This invention provides an improved method of effecting this to producea wrinkle coating on articles. Y Y v In the accompanying drawings:

Figure l is avertical sectional view of anarticle having a smoothsurface coating;

Figure 2 is a vertical sectional view through an oven-showing the mannerof exposing the material to heat and ultra-violet ray lamps for dryingcoated articles;

Figure 3 is a similar sectional view illustrating the arrangement forbaking nishes which arey applied to both sides of panels or sheets;

Figure 4 is a similar view in section taken through a circular ovenhaving heat and ultraviolet ray lamps mounted around the interior wallto concentrate the heat and light on irregular shaped articles which areto be dried to a wrinkle finish;

Figure 5 isa similar view of an oven as in Figure 1, illustrating theutilization of heat lampsvalone with means for admitting oxygen toenrich the atmosphere in contact with the coated article;

Figure. 6`is an elevation view, partly in section, of an oven showingthe arrangement for admitting heated air which has been enriched withoxygen and having an oxidation catalyst incorporated therewith fordrying' coated articles to produce a wrinkle nish.

Referring to the drawings in detail, Figure l shows a panel or article Ahaving a smooth surface coating B. In Figures 2, 3 and 4 an Aovengenerally designated I0 is illustrated for drying coated articles,according to my invention, to accelerate-the drying of the coating to ahard smooth illm or wrinkle surface-finish.

'I'he ovens are constructed in the forml of tunnels or rectangularenclosures having suitable means for lsupporting and lconveying coatedarticles into and out of the drying oven. Heat is supplied by banks ofreflector equipped incandescent lamps i I which are arranged within theenclosure so -as to concentrate the rays onto 4 the surface of thecoated articles. Preferably laments are used for this purpose.

Interposed between the heat lamps il are u1- tra-violet irradiatingmeans I2. Any suitable source of ultra-violet ray producing -means canbe employed, the quartz mercury arc. lamp of the Cooper-Hewitt typebeing readily applicable. Ultraviolet irradiation from a carbon arc mayalso be used if desired. 'I'he heat lamps and Ainfra-red radiatingelectric lamps having carbon ultra-violet lamps maybe arranged inalternate relatio` ship so as to provide even distribution of hea andultra-violet irradiation of the atmosphere adjacent the articles beingdried. In general the lamps should be placed between ten and thirtyinches from the coated article. The light drying venclosures are nothermetically sealed so as to permit the ready exit of products ofoxidation during drying of, the coated articles.

In the modification illustrated in Figure 4 the oven l! is of circularconstruction and the heat and ultra-violet lamps are maintained inspaced relationship around the walls so as to effectively direct therays against all sides of an irregular shaped article. The lamps may, ifdesired, be

made adjustable so that their position can be changed relative to eachother. It will also be understood that the number of heat lamps orultra-violet lamps may be varied as required to increase or decrease thetemperature of the enclosure and the ultra-violet irradiation of theatmosphere.

Ultra-violet irradiation provides means for ionizing the air in contactwith the coating film forming ozone which accelerates the surface dryingby auto-oxidation. This oxidation of the coating is enhanced by the heatlamps resulting in rapid surface drying of the film which expandslaterally due to the oxidation and increased volume to produce folds orcreases over the entire llm surface. By this method of accelerating thesurface drying rate of films, coating compositions particularly of thedrying oil type, which under the ordinary drying and baking temperaturesdo not produce a wrinkle finish, are made to dry to a satisfactorywrinkle finish. Heretofore in the compounding of wrinkle finishes, theuse of substantial amountsof tung oil, oiticica oil or synthetic wrinkleresins of the drying oil acid modiiled type has been required for theproduction of wrinkle finish coating compositions. By the improvedmethod of accelerating the surface drying rate of coating compositionsaccording to this invention, the use of large amounts of these expensivedrying oils is unnecessary and in general may be substituted by linseedoil, soya bean oil and the like non-wrinkling oils.

In Figure 5 the baking oven I4 comprises an endless conveyor l5 which isarranged for conveniently moving the coated articles into and out of thelight drying enclosure. In this instance ultra-violet lamps are omittedand the heat lamps Il alone used. Oxygen or ozone enriched air isintroduced into the drying oven as at I6; Where drying oil compositionsused in coating the articles comprise raw China wood oil or similardrying oils which have not been heat .treated to a suiliciently hightemperature to eliminate crystallization or gaschecking, the nitrogendioxide content of the atmosphere may be maintained above 4 to 5 partsper million parts of air which brings about crystallization or gaschecking of the nlm. Ordinarily, however, gas checking will not beproduced even with articles coated with raw drying oils due to thecomparatively short period of time between the evaporation of thesolvents and the beginning of oxidation.

The usual drying oil coating compositions comprise metallic oxidationcatalysts such as cobalt, manganese, lead in the form of linoleate oracetate, alone or mixtures of these. 'I'hese driers enhance thewrinkling and materially speed up the drying yof the lm especially whendried by the use of heat lamps as in'this invention.V T0

accentuate surface oxidation atomized organic solutions of metallicdriers such as cobalt or manganese in the form of oleates, stearates.naphthenates. etc. may be introduced into the drying ovens to form apart of the atmosphere in contact with the coating illm. Metal drierscolloidally dispersed in an oil soluble solvent such as butyl alcohol orpetroleum spirits may be utilized.

This modification is illustrated in Figure 6 wherein the requiredtemperature in the oven I1 for baking the coated articles is maintainedby the introduction of preheated air, as shown. into which has beenintroduced oxygen or ozone enriched air together with an oxidationcatalyst. It will be understood that heat lamps may be employed togetherwith the circulating heated air .for maintaining the temperature in thebaking oven I1 if desired. A fan generally designated I8 may be employedfor forcing the circulation of air through the heating element I9 andcirculating it through the oven, as shown in Figure 6.

The oxidation catalyst which may be introduced into the oven maycomprise atomized organic peroxide such as acetyl or phthalyl or benzoylperoxide dissolved in benzol or toluol. This solution may be suitablysprayed into the oven chamber or carried into the oven by the oxygen orstream of air being conducted into the oven. In this manner sufficientamount of oxidation catalyst can be placed in contact with the surfaceof the coating lm on the articles to accelerate the surface oxidationand drying of the coating to produce a satisfactory wrinkle finish. Thiswill be enhanced further by the use of coating compositions comprisingmetallic driers. Clear varnishes as well as pigmented enamels may bedried to a wrinkle finish.

'Ihe usual temperatures employed in producing wrinkle finishes on metalsurfaces are of the order of 150 up to approximately 450 degrees F. Forproducingwrinkle finishes on Wood, paper and similar materials somewhatlower temperatures, such as to 150 degrees F. may berused. The elevatedtemperatures produce a more rapid oxidation of the film surface andpromote the production of wrinkle finishes and in general accentuate thewrinkle. Lower temperatures of baking 4usually require higherpercentages of drying oils having poly-conjugated double bond structurein order to suilciently accelerate the oxidation rate of the filmsurface during the treatment to produce a wrinkle or irregular surfacefinish.

As an alternative manner of contacting the surface of the coating nlmwith the oxidation catalyst, a thin lm of .the solution carrying thecatalyst may be lightly sprayed over the coating just prior tointroducing the coated articles into the baking oven. Further in placeof the oxidation catalyst mentioned, oxidized turpentine which is highin active peroxide of oxygen may be utilized with or without theaddition of metallic drier.

It will be understood that I desire to comprehend within my inventionsuch modifications as come within the scope of the claims and theinvention.

Having thus fully described my invention, what I claim as new and desireto secure by Letters Patent is:

l. The method of producing a wrinkle finish comprising drying oxidizablecoating compositions in the form of a nlm including the steps of heatingair, introducing oxygen in said air to increase the oxygen content abovethat normally assess? s present in ordinary airkadmixing an oxidationcatalyst into said air and subjecting the coating film to said air intowhich the oxygen and catalyst have been introduced. 2. The method ofproducingwrinkle iinishes comprising drying oxidizable compositions inthe formvof a fllm comprising the steps of concentrating infra-red heatrays onto said lm. heating air and Csimultaneously introducing oxygen'thereinto to increase the oxygen content above that normally present inordinaryair, and subjecting the coating film to said air into whichVoxygen has been introduced to eilect drying 'of the coating to awrinkled surface.

3. The method lof producing wrinkle finishes from oxidizable paints,varnishes. and resinous compositions which comprises the steps offocusing heat rays on to the, iilm surface. heating air.-

incorporating oxygen in said air,to increase the oxygen content abovethat normally present in air, concurrently addingoxidation lcatalystinto ,said heated air and 'subjecting thecoated articles thereto toproduce a wrinkled surface coating.

4. The method'of producing at wrinkle nnish from coating compositionscomprising non-wrinkling oils consisting of dryingl the coating in theform of a nlm andaccelerating the surface drying ofthe nlm byheating'the air in which the' 3 coating iilm is to be dried, introducingoxygen into said air to increase the oxygen content of the .heated airabove that vnormally present in ordinary air, and spraying the coatingiilni with an oxidation catalyst immediately prior to drying said illmtoeii'ect accelerated oxidation and drying of -theiilm at its-surfacewhereby an irregular wrinkled surface isfgproduced.'1

5. The method of producing a wrinkle nish oy treating an varticle havinga illm of the coating composition thereon, comprising sprayinga lightcoating of a solution containing an oxidation catalyst over said coatinglm Just' prior to drying said coating nlm, subjecting the film to heatedair, introducing oxygenpinto said air and drying the coating lmin saidheated air to produce folds or creases in the surface of the tllm and nform an irregular wrinlgled finish.

6. A method of Lproducing 'a wrinkle nish by accelerating the surfacedrying of the composition in theform of a-illm comprising the steps ofconcentrating infra red'heat rays onto the l' surface of the ilim andsimultaneously subjecting said nlm to air in which oxygen contenthasbeen substandaliyincreased above that normally 2 a constituent part ofair. Y

' Folsom E. DaUsmoNn.

